Terpolymers of ethylene-carbon monoxide-X (“E-CO-X”), where X is third monomer, such as vinyl acetate or methyl methacrylate, are generally made from ethylene, carbon monoxide (“CO”), and vinyl acetate or methyl methacrylate feeds. These polymers are prepared using free radical initiators at high pressures and temperatures. Furthermore, these polymers are random, which are generally difficult to make using organometallic catalysts. The E-CO-X polymers formed from free radical polymerization are useful as polyvinyl chloride (“PVC”) modifiers and degradable films.
Geminally disubstituted olefin monomers, such as isobutylene, are known not to be readily polymerizable by free radical polymerization mechanisms. Instead, such disubstituted α-olefins are typically polymerized and copolymerized by cationic or carbocationic polymerization with Lewis acid catalyst systems known to initiate the formation of carbocations.
PVC is one of the most economic, versatile and useful commodity polymers for a wide variety of applications. Presently, PVC is the second largest thermoplastic resin manufactured behind polyolefins, with a world-wide capacity of approximately 31 millions tons. The exceptional versatility of PVC is partially due to its ability to form stable solutions of wide percentage composition with a variety of plasticizers and additives.
Plasticizers are added to plastics to improve flow and, therefore, processability and flexibility, and to reduce the brittleness of the product. This is achieved by lowering the glass transition temperature (Tg) below room temperature, thus achieving a change in properties from that of a hard, brittle, glasslike solid to that of a soft, flexible, tough material. There are presently about 450 different plasticizers produced worldwide, although only about 50 of these are classified as commercially important. Approximately 90% of these products are used in the production of plasticized or flexible PVC.
More than 95% of these plasticizers are very low molecular weight (<500) monomeric esters. One of the problems with low molecular weight plasticizers is their tendency to volatilize during the various processing steps in manufacturing flexible PVC articles. Volatilization losses in end uses can be even greater. Also, plasticizers leave by volatilization, migration, and extraction. Plasticizers can migrate into other materials, such as other PVC, polystyrene, acrylics and ABS, or even some nitrocellulose based paint finishes. It is desirable to have products with lower volatility, less migration and more extraction resistance. Using high molecular weight polymers minimizes the volatility problems.